Generally, in a manufacturing process of a semiconductor device, photolithography is used to form a fine pattern. Multiple substrates called transfer masks are usually utilized in forming the fine pattern. In miniaturization of a semiconductor device pattern, it is necessary to shorten the wavelength of an exposure light source used in the photolithography, in addition to miniaturization of a mask pattern formed in the transfer mask. Shortening of wavelength has been advancing recently from the use of KrF excimer lasers (wavelength: 248 nm) to ArF excimer lasers (wavelength: 193 nm) as exposure light sources in the manufacture of semiconductor devices.
As for the types of the transfer mask, a half tone phase shift mask is known in addition to a conventional binary mask having a light shielding pattern made of a chromium-based material on a transparent substrate. Molybdenum silicide (MoSi)-based materials are widely used for a phase shift film of the half tone phase shift mask. However, as disclosed in Patent Document 1, it has been discovered recently that a MoSi-based film has low resistance to exposure light of an ArF excimer laser (so-called ArF light fastness). In Patent Document 1, the ArF light fastness of the MoSi-based film is enhanced by subjecting the MoSi-based film after formation of a pattern to a plasma treatment, a UV irradiation treatment, or a heat treatment to form a passivation film on a surface of the pattern of the MoSi-based film.
In the half tone phase shift mask, a light shielding band is often provided in a peripheral portion around a transfer pattern forming region where a phase shift pattern is formed. Even within the transfer pattern forming region, a relatively large-size phase shift pattern may have a smaller light shielding pattern laminated thereon. Patent Document 2 discloses a mask blank for manufacturing a half tone phase shift mask, which has a thin film structure including, from the substrate side, a metal silicide-based transfer mask film (light semitransmissive film), a light shielding film formed from a chromium-based compound, and a hard mask film formed from a silicon compound.